This invention pertains to an improved process for hydrating olefins and more particularly to a phosphoric acid supported catalyst which has both high activity and high crush strength.
Supported phosphoric acid catalysts have been widely and successfully employed commercially for the past 30 years in the direct hydration of ethylene to ethanol, as well as the direct hydration of other olefins. Different silica based supports have been used including diatomaceous earth, usually in conjunction with a clay binder, silica gel and various alumino silicates. Generally the support is calcined to impart physical integrity and then leached with a mineral acid to reduce the content of metallic impurities prior to impregnation with phosphoric acid.
Although phosphoric acid catalysts, such as those described above, have been used commercially, there is a continuing need for an olefin hydration catalyst which combines several properties, viz., reasonably long life regarding its catalytic activity, sufficient mechanical strength to withstand crushing during preparation and use, and chemical stability and inertness during the hydration process.